Process for producing plate glass



Jall- 24, W, H ALL|SON PROCESS FOR PRODUCING PLATE GLASS Filed July '7, 1951 hol-leg l Patented Jan. 24, 1933 UNITED STATES WILLIAM H. ALLISON, `or CHARLESTON,

PATENT OFFICE p WEST VIRGINIA, AssIGNOR 4To lLIiBEY: s OWENS-FORD GLASS COMPANY, or TOLEDQOHIO, A CORPORATION or OHIO PROCESS Vron TBOLUOING `PLATE erLnSs.V

, Appiieafibn mea Iuiy 7, ieais'riai'No. 549,235.

The present invention relates to ,an im'- proved process for producing plate glass.

In the productionof plate glass according to the continuous system, a plurality of sheets of glass to be surfacedaremounted upon a series or train of carsorv tables and passed in a definite substantially horizontal path first .beneath a series of grinding runners and then beneath a series of -polishing runnersto surface one side ofthe sheets,y after whichV the saidl sheets are turnedover yupon the tables and again passed 'beneath' the same or a second series of-grinding and polishing run# ners to surface the 'secondfsde f Thecgrinding runners employed in the continuous system referred to abovefare rela# tively`very heavy, being ordinarily in --the form of solid discs constructed of cast iron or the like. These runners Vare also Vusually carried at the lower ends l'of vertically disposed-drive spindles in such a manner that they arepermitted a limited amount. of uniL versal rocking and vertical bodily movement.

The sheets of glass which are to be ground Vandypolished are` usually termed lplate vglass blanks, landV heretofore thesel blanksr have been 'formed so that'the ,opposite surfaces thereof were relativelylat and substantially parallel withOne-another. However@ have found that when Vusing ai "plate 'glass' blank which is relativelythinner Vat' its 4centerfthan at the opposite 4sides Vthereof' or, inother words, when the surfacel of the sheet to'be ground and polished is slightly concave, that the grinding runnersl seat themselves-better upon theglass during the grinding thereof, as a-result of which the tendency of therunners to rock upon the vsheets is materially lessened and, as a consequence, breakageof the glassfrom this cause` is'reducedto a minimum. Therefore, the principal aim andi-object'of this invention is the product-ionlofa plate glass blank A'ofv the `above character which; relatively thinner 'f at its center than atgthe l sides thereof, Vand `the subsequent grinding and polishing of the Opposite faces ofthis blankin theV usual fashionto render them plane and parallel with? one another. y Other'objects and 'advantages of the invention-'will become more apparent during the course of the lfollowing description `when takenin connection with the accompanying 'In' the drawing forming a part of this `apfr plication and wherein'like numerals aref'lemf' ployedto designate like parts throughoutthe same, l Fig. l is a vertical through one type of sheet forming apparatus which may be employed in theV carrying out of the'present invention, o f Y 1 V Y Fig. 2 is a plan View of the sheetlforming rolls, Y Sis a representation of one form of grin ing apparatus, and

[Fig-4L 's a sect`onal View of a finished ground andfpolished sheet. f 'i Y V Referring tothe drawing, the numeral-5 designates a relatively shallow workingreceptacle or pot'containing'a mass of molten glass 6 supplied thereto from any suitable type of melting` furnace 7. In Order to more eectivelyl control the temperature of the molten-bath 6,'the working receptacle 5 is preferably arrangedvwithin 'a heating comypartment 8 being supported thereinupon stools9.

Positioned above the mass of molten glassG :and inrelatively close proximity to the sur-r longitudinal section lao face4 thereof are the two forming rolls 10 and 11, preferably, although not necessarily,vdi`sj` posed side side in substantial rhorizontal alignment wth one another as shown. `These rolls are also preferably positively driven in such a manner thatf after a sheet hasbeen l.started by the' use of abait or other means as 1s well understood in the art, a relatively thick heavy body of glasslZwill be continuouslydrawn or moved vertically from the receptacle 5 between the :said rolls and reduced 'thereby-to sheet form as indicatedat 13; The rollslOand 11 are adjustablymountedrelative to one another to permit the production `Y`ofthe `desired thickness 4of sheetfwhich is tance and then-deflected'into the-horizontal plane about a bending roll 14 and carried along upon a plurality of conveying rolls 15 into and through .an annealing leer. Of course, the bending roll 14 could be omitted, if desired, and the sheet deflected into the horizontal plane about forming roll l0.

The type of rolling machine generally de- 'l scribed hereinabove and illustrated in the stantially flat and parallel. VHowever, ac-

cording to thepresent invention, the forming "rolls 10 and 11V are of such a constructionthat the sheet 13 formed thereby is relatively thinner at its center than at the opposite sides thereof as clearly shown in Fig. 2. Thatis to say, the sheet forming rolls taper fromtheir lcenters toward their opposite ends so'that the opposite surfaces Vof theglass sheetare relativelyconcave, withthe concavity or recess in each face increasing in depth fromr `tle side edges of the sheet to the center there- .i When the sheet leaves the forming rolls l() and 11, it is of course still relatively plastic, and therefore the bending roll 14 and conveying rolls 15 arepreferably of the saine construction as the formingrolls so that they Y will serve to support the sheet in -a manner Y to prevent sagging of the thinnercentral portion thereof with respect to the thicker side portions until the said sheet-has become sufficiently set to support its own Weight. 1

After the continuous sheet 13has been thoroughly' and completely annealed, it 'out' transversely into individual sheets and these sheets'are vespecially Vwell adapted; for use as .plate'glass blanks. Moreover,-this particular. type of blank Yis very desirable foruse in Vthe continuous system for surfacing sheet glass. n As pointed out above, in this system a plurality of cars or tables carrying the glass VSheets to be treated upon the upper surfaces i thereofare passed first beneath a series of grinding runners and then beneath a series of polishing runners to surface one side of the sheets, after which the said sheets are turned over upon the tables and again passed beneath the same or a second series of grindin and-pohshing runners Vto surfacefthe secon Vside.-

Y im

designates oneof: the tables of the continuous system, which is here shown as being mountedupon wheels 17` adaptedto run along the rails-18. The glass sheets 19V constituting the plate glassblanks are` adapted to be secured In '3 of the drawing, the vnumeral :16'

. Lacasse After the glass sheets have been secured upon the tables, they 'are adapted to be passed first beneath a series of the grinding runners 2l and thence beneath a series of polishing runners l(not shown) Vto* surface theupper sides thereof.v During this grinding' and polishing, the recess or depression 23 in the upper face of the sheetwill be removed sothat when the.' surfacing thereof has been completed, the said face of the sheet will be fiatV or plane.- The sheets arevthen turnedover upon the tables and again secured-thereto, after which the second side-is treated inthe same manner` so asv to render the'sheet of a y uniform thickness throughout, ywith they lopposite surfaces thereof being plane and parallel with one another as illustrated in Fig. 4. As set forth above, when usingl plate glass blanks Which larev slightly concave or, in other Words, relatively thinner Vat :their centers than at theirr opposite sides, the relatively heavyvgrinding runners *tend to seat themselves better upon the glass'during the grinding thereof so that thereis less rocking of said runners and consequently less breakage of the glass. Y Y

The present invention is, of course, not restricted to the use of either the. particular type of sheet formin means or tothe particular type of Vgrin ing means herein disclosed. K Onthecontrary, theseare only exemplary forms ofapparatus which can be employed lin :carrying out this invention.

The .process-and apparatus disclosed herein for ,producing the glass sheets or .plate glass blanks which are-,relativelyI thinnerattheir centers thany at the opposite sides thereof, are not beingjolaim'ed'per sein-,this application since' they. constitute the subject-matter of a. copending ap lication filed by meson July 7,1932,-Serial 0.549,234. Y

-' Itis tombe understood thatthe form of the Y inventionherewith shown' and described is to be takenas the preferredembodiment of the same, and that Ivarious changes inthe shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention Ior the scope of the subjoined f claims.

1. The processof producing plateglass,` which consists in first forming a Iplate glassl blank comprising asheet of glass,"the surface thereof which is to be l.ground andpolished being concave, mounting the sheet lioV 'l horizontally upon fa support with the concave surface'uppermost, then passingv they said sheetl forwardly in a definite substantially horizontal path, in subjecting-the upper surface of said sheet during the forward travel 1 thereof to a grinding action to remove thel depression therein and render it plane or flat by bringing into engagement therewith successively a plurality of revolving rinding disc runners which operate upon tie glass sheet across its entire width, and in then pol-` ishing the ground surface. t

2. The process of producing plate glass, which consists in first forming a plate glass blank comprising a sheet of glass which is relatively thinner at its center than at the opposite sides thereof, mounting the sheet horizontally upon a support and carrying it forwardly in a denite substantially horizon-V tal path beneath and in contact successively with a plurality of grinding machines arranged in series above the said sheets and each provided with a revolving disc runner f which operates upon the glass sheet 4across its entire width to remove the depression therein and render the said surface plane or fiat and in then polishing the ground surface.

Signed at Charleston, in the county of Kanawha and State of West Virginia, this 3rd day of July, 1931.

WILLIAM H. ALLISON. 

